Ralph_Slate - 1:09 am on Aug 22, 2012 (gmt 0)
I tried something a little different with my well-known forum software. I noticed that there were a lot of duplicate pages being returned when I searched for exact phrases - between the print version, archive version, SEO-friendly URL version, etc. - so I put an apache directive in the forum directory that basically returns X-Robots of "nofollow, noindex" on every forum page EXCEPT the forumlist, threadlist, and thread pages.
It takes Google forever and a day to actually remove pages from their index, so only time will tell if this was a good strategy, but I counted something like 100,000 pages returned from my site: search that included the forum subdirectory, but there are just 15,000 forum threads, meaning that I had somewhere near 85,000 pages of useless crap indexed.